Marine outboard motors have a power head whose output crankshaft is coupled to an elongate vertical power shaft. The rotating shaft passes through a mid-section to a lower unit where it is coupled by a right angle gear assembly to the horizontal propeller shaft that turns the propeller. The shaft is well supported at its two ends by rotary bearings. To accommodate some marine applications such as a high transom, the outboard motor may be configured with a long shaft so that the lower unit is at an increased distance from the power head. A spacer is generally inserted between the lower unit and the mid-section along with the longer shaft. Problems occasionally arise with the increased length, power, and speed of rotation of these long shaft configurations. It has been found that high torque and great rotary speed may cause the shaft to bow out between its unsupported ends from centrifugal forces. When a resonant frequency of rotation is reached, even very slight unbalances in the rotating shaft causes slight bending that becomes cumulative. The term “whipping” is applied to this phenomenon. When it exceeds a certain limit, it may result in failure.